1. Field of the Invention
The present invention relates to carrier trolleys placed at the disposal of customers of self-service stores for transporting selected products and merchandise. Trolleys of this type consist of a large carrier basket located at a predetermined height with respect to a base frame on which the wheels are fixed, an operating handle-bar being provided at the top rear end of the trolley.
2. Description of the Prior Art
In order to reduce the bulk of trolleys when they are placed in readiness for use, they are usually designed so as to fit one inside the other. To this end, the rear vertical wall of the carrier basket is constituted by a flap which is hinged along its top edge and can thus be lifted in order to permit engagement of the front end of the carrier basket of another trolley. The base frame of a self-service trolley also has a shape which permits nesting of a number of trolleys by engagement of the front end of each trolley within the rear end of another trolley.
In order to facilitate the combined displacement of an entire row or "train" of interengaged trolleys, it has already been proposed to provide means for lifting the rear wheels of each trolley except for those of the trolley located at the rear end of the train.
Thus the base frame of the trolley described in French patent No. 2,537,076 comprises two side members, the inclined front portion of which is intended to engage beneath a horizontal cross-member forming part of the base frame of the trolley located in front at the time of engagement of the front end of one trolley in the rear end of another trolley placed in front, thus having the effect of lifting said rear end. However, this solution entails the need to ensure that the side members of the base frame are inclined at a strictly constant angle. If this condition is not satisfied, engagement of a rear trolley may fail to lift the rear wheels of the front trolley. However, since the side members of the base frame are formed by elbowed wires, it proves difficult in practice to ensure that the angle of slope of the baseframe side members at the rear end is continuously maintained at a constant and perfectly accurate value under actual service conditions.